Editorial changes to html-page-lang-valid

_rules/html-page-lang-valid-bf051a.md

@@ -22,11 +22,11 @@ acknowledgements:
 
 This rule applies to any [document element](https://dom.spec.whatwg.org/#document-element) if it is an `html` element that:
 
+- has a `lang` attribute that is neither empty ("") nor only [ASCII whitespace](https://infra.spec.whatwg.org/#ascii-whitespace); and
 - is in a [top-level browsing context](https://html.spec.whatwg.org/#top-level-browsing-context); and
-- has a [node document](https://dom.spec.whatwg.org/#concept-node-document) with a [content type](https://dom.spec.whatwg.org/#concept-document-content-type) of `text/html`; and
-- has a `lang` attribute that is neither empty ("") nor only [ASCII whitespace](https://infra.spec.whatwg.org/#ascii-whitespace).
+- has a [node document](https://dom.spec.whatwg.org/#concept-node-document) with a [content type](https://dom.spec.whatwg.org/#concept-document-content-type) of `text/html`.
 
-**Note:** `html` elements within `iframe` and `object` elements are not applicable as `iframe` and `object` elements create [nested browsing contexts](https://html.spec.whatwg.org/#nested-browsing-context). However, as these elements are meant to provide a layer of isolation, the declared language of their [parent browsing context](https://html.spec.whatwg.org/#parent-browsing-context) will likely not be inherited, making it possible for non-valid `lang` attributes in [nested browsing contexts](https://html.spec.whatwg.org/#nested-browsing-context) to also cause accessibility issues.
+**Note:** `html` elements within `iframe` and `object` elements are not applicable as `iframe` and `object` elements create [nested browsing contexts](https://html.spec.whatwg.org/#nested-browsing-context). However, as these elements are meant to provide a layer of isolation, the language of the [parent browsing context](https://html.spec.whatwg.org/#parent-browsing-context) may not be inherited. This should be tested separately.
 
 ## Expectation
 
@@ -42,6 +42,7 @@ _There are no major accessibility support issues known for this rule._
 
 ## Background
 
+- [Understanding Success Criterion 3.1.1: Language of Page](https://www.w3.org/WAI/WCAG21/Understanding/language-of-page.html)
 - [H57: Using language attributes on the html element](https://www.w3.org/WAI/WCAG21/Techniques/html/H57)
 - [BCP 47: Tags for Identifying Languages](https://www.ietf.org/rfc/bcp/bcp47.txt)
 - [MDN: `lang` attribute](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/lang)